Power Converter Controller Regulating Output Current via Dynamic Switching Period
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Solution Overview
Problem
Conventional power conversion systems for LED lighting struggle to achieve high efficiency, power factor, and low total harmonic distortion, as they often fail to maintain a stable output current due to variations in input voltage and switching periods.
Innovation Solution
A system controller is implemented to regulate the power conversion system by maintaining a constant multiplication product of the duty cycle and on-time period, using a ramp-current generator and ramp-signal generator to adjust the switching periods and ensure a stable output current, thereby reducing total harmonic distortion and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional power conversion systems use fixed switching periods, then the control is simple, but the output current becomes unstable due to input voltage variations
Solution Approach 1:
The patent implements dynamic switching period adjustment by varying the switching period based on the rectified input voltage magnitude. The controller adapts the switching period in real-time to maintain stable output current, transforming the fixed switching period into a dynamic parameter that responds to input conditions.
Solution Approach 2:
The patent changes the switching period parameter according to the rectified input voltage. By making the switching period a variable parameter rather than a fixed value, the system can compensate for input voltage variations and maintain stable output current.
2Stability of the object's composition
If the switching period is adjusted to maintain stable output current, then the output current stability improves, but the control complexity increases
Solution Approach 1:
The patent uses feedback from the rectified input voltage signal to adjust the switching period. The controller monitors the input voltage and automatically adjusts the switching period accordingly, creating a closed-loop control system that maintains stable output current without requiring complex external control circuits.
Solution Approach 2:
The system uses its own rectified input voltage signal to control the switching period adjustment. The input voltage itself becomes the control reference, eliminating the need for separate voltage sensing circuits or complex control algorithms, thereby reducing overall system complexity while achieving stable output current.
3Device complexity
If conventional systems do not adjust switching periods, then the device complexity remains low, but total harmonic distortion exceeds 10%
Solution Approach 1:
By dynamically adjusting the switching period based on input voltage, the system reduces harmonic distortion in the input current waveform. The adaptive switching period ensures more sinusoidal current draw from the AC source, lowering total harmonic distortion while maintaining relatively simple control architecture.
4Loss of energy
If the output current is not regulated, then the system efficiency is lower, but the control mechanism is simpler
Solution Approach 1:
The patent changes the switching period parameter to optimize system efficiency. By adjusting the switching period according to input voltage conditions, the system improves power transfer efficiency and reduces energy losses while maintaining a relatively simple control mechanism that uses the existing rectified voltage signal.
Data Source
AI summary
Systems and methods are provided for regulating power conversion systems. A system controller includes: a first controller terminal configured to receive a first signal related to an input signal for a primary winding of a power conversation system; and a second controller terminal configured to output a drive signal to a switch to affect a current flowing through the primary winding, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed (e.g., being turned on) in response to the drive signal during the on-time period. The switch is opened (e.g., being turned off) in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. The system controller is configured to keep a multiplication product of the duty cycle and the duration of the on-time period approximately constant.